Treatment period A: 2-week treatment with HFA-QVAR (TEVA Pharma) 200 μg b.i.d. Treatment period B: 2-week treatment with HFA-Clenil (Chiesi) 400 μg b.i.d. Treatment period C: 2-week treatment with HFA-Fluticasone (GlaxoSmithKline) 250 μg b.i.d.